Gaskets provide a mechanical seal that fills the space between two mating surfaces. They may be provided to prevent leakage from or into the pieces which place the gasket under compression. Gaskets may allow for less than perfect mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced from cutting sheet materials, such as gasket paper, rubber, silicon, metal, core, felt, neoprene, nitrile rubber, fiberglass or plastic polymer, such as polychloro, trifloro ethylene.
FIGS. 1A and 1B illustrate a prior art tabular gasket TA. The prior art tabular gasket is seen to have a planar top surface and a planar bottom surface with both the top and bottom surfaces spaced apart a uniform distance and generally parallel. The prior art tabular gasket is intended to be placed between a workpiece WP and a base B. Referring to FIG. 1B, it can be seen that the tabular gasket is placed under compression when the workpiece is fastened to the base, typically by a multiplicity of fasteners torqued down to a proper torque rating.
The workpiece may be an antenna mount for engagement with the exterior of an aircraft whose fuselage comprises a generally flat or slightly curved base B. Applicants' gaskets are typically pre-cured gel, such as a pre-cured polyurethane formulation that retains its soft and tacky physical properties throughout the service temperature of the product. Such a material is disclosed in previous patents issued to Applicants, including U.S. Pat. Nos. 6,530,517; 6,695,320; and 7,229,516, incorporated herein by reference. They are typically pre-cured polyurethane and may contain a skeleton material, such as a metallic or non-metallic mesh material between the top and bottom surfaces.
In FIG. 1B, it is seen that, with the uniform thickness of tabular gasket prior art, compression around fasteners provides primarily a perimeter escape for squeeze out gasket material. The prior art gasket tends to flatten over time and the bolts or fasteners need to be re-torqued. Indeed, there may be a wait as much as 15 minutes for squeeze out to be generated in the prior art gaskets, so as to allow the re-torque of the fasteners to sufficient tightness.